MEIOSIS 11-4 Making gametes Planaria animation:FamilyRemember from Chapter 1: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________ REPRODUCE ASEXUAL REPRODUCTION Bacteria reproduce using __________________________________ Budding & regeneration are used by plants and animals to reproduce asexually (mitosis) Planaria animation:BINARY FISSION BINARY FISSION & MITOSIS Produces cells that are __________ copies of parent cell identical SEXUAL REPRODUCTION Combines genetic material from 2 parents (sperm & egg) so offspring are genetically __________ from parents DIFFERENT Family image from: ADVANTAGES OF SEXUAL REPRODUCTION Allows for variation in population Individuals can be different Provides foundation for EVOLUTION Allow species adapt to changes in their environment EGG + SPERM If egg and sperm had same number of chromosomes as other body cells... baby would have too many chromosomes!Image by Riedell MEIOSIS is the way to make cells with the number of chromosomes for sexual reproduction DIPLOID & HAPLOID Most cells have 2 copies of each chromosome = ______________ (one from mom; one from dad) All BODY (___________) cells are diploid DIPLOID2n HOMOLOGOUS CHROMOSOMES = SOMATIC DIPLOID & HAPLOID Some cells have only one copy of each chromosome = _____________ All sperm and egg cells are haploid HAPLOID1n MITOSIS Makes ___ cells genetically _________ to parent cell & to each other Makes ___ cells Makes __________ Used by organisms to: increase size of organism, repair injuries, replace worn out cells2 identical 2n SOMATIC (body) MEIOSIS Makes ____ cells genetically different from parent cell & from each other Makes _____ cells Makes ______________ Used for ____________ 4 1n Gametes (sperm & eggs) sexual reproduction WHAT MAKES MEIOSIS DIFFERENT ? 1.Homologous chromosomes pair up during ________________ Images modified from:This group of FOUR (4) chromatids is called a _________________ TETRAD PROPHASE I WHAT MAKES MEIOSIS DIFFERENT? 1. Exchange of DNA between homologous pairs = _____________ during PROPHASE I CROSSING OVER Allows shuffling of genetic material HOMOLOGOUS CHROMOSOMES Image modified by Riedell SAME SIZE SAME SHAPE CARRY GENES for the SAME TRAITS BUT ______________! (Dont have to have the SAME CHOICES)NOT IDENTICAL CROSSING OVER Image modified by Riedell Allows for_________________ in different combinations After crossing over, chromatid arms are________________ anymorerearranging of DNA NOT IDENTICAL Separation of homologous pairs (Anaphase I) INDEPENDENT ASSORTMENT Separation of homologous pairs at ANAPHASE I Lots of different combinations are possible! This is why you dont look exactly like your brothers and sisters even though you share the same parents! WHAT MAKES MEIOSIS DIFFERENT ? Crossing over MEIOSIS results in =______________________________ So daughter cells are ______________ from parents and from each other different GENETIC RECOMBINATION WHAT MAKES MEIOSIS DIFFERENT ? INTERPHASE II (No S) shorter CELL DIVIDES TWICE, BUT ONLY COPIES ITS DNA ONCE G1G1 G2G2 S PM A T C G1G1 MITOSIS: MEIOSIS: SG2G2 PM ATC PM A TC ( I ) ( II )G1G1 G2G2 Ways Meiosis is different? Homologous pairs match up & trade DNA (CROSSING OVER) in PROPHASE I create genetic recombination INTERPHASE II- no S stage (Dividing TWICE but copying DNA once) produces 1n cells MAKING SPERM & EGGS ___________________= MAKING MATURE SPERM Mature & grow flagella SPERMATOGENESIS POLAR BODIES Produces: 1 good egg 3 CYTOPLASM DIVIDES UNEVENLY __________________ = MAKING a MATURE EGG OOGENESIS Sperm donates mostly DNAWHY MAKE ONLY ONE GOOD EGG? Most of the cell parts and nutrients needed for baby come from EGG! Self digest Using ________________ POLAR BODIES DEGENERATE (DIE) LYSOSOMES = __________________ cell suicide for good of organism APOPTOSIS